Multiple gap circuit breaker



Fflb. 5, 1935. p 1 551-2 r AL 1,990,451

MULTIPLE GAP. CIRCUIT BREAKER File d Feb. 25, 1932 s Sheets-Sheet 1 Feb. 5, 1935. P. L. BETZ El AL 1,990,451

MULTIPLE GAP CIRCUIT BREAKER Filed Feb. 25, 1932 3 Sheets-Sheet 2 6a TIIIIIIIIIIIIIHINIIIHIIIIlllmllllgZ mwytms Feb. 5, 1935.

P. L. BETZ ET AL MULTIPLE GAP CIRCUIT BREAKER Filed Feb. 25, 1932 5 Sheets-Sheet 5 NNNA-M, N I

gvwc/wtoms as 7 0 m, W was WW5 Patented Feb. 5, 1935 UNITED STATES PATENT OFFICE MULTIPLE GAP CIRCUIT BREAKER tion of Maryland Application February 25, 1932, Serial No. 595,186 30 Claims. (Cl. 200-145) This invention relates to electrical apparatus and more particularly to a multiple gap circuit breaker which can be used with either alternating or direct current.

It has heretofore been proposed to provide multiple gap circuit breakers in which the voltage of the circuit to be interrupted is used to overcome the anode potential drop of the series arcs with the result that no voltage is left to maintain the arcs. Such constructions are based on the theory that a resistance or counter electro-motive force is concentrated at the positive electrodes of the plurality of gaps, and that a comparatively small part only of such coimter electro-motive force exists in the flame of the arc. In these constructions the number of gaps provided is based on the assumption that at least forty volts are required to overcome the counter electro-motive force at the surface of the positive electrode of each gap.

However, it has since been found that this positive electrode, or anode, potential drop is a variable quantity and depends upon the size and shape of the anode as well as the nature of the gas and degree of ionization, and may be positive or negative in sign, so that it is possible to have an electric arc with practically no anode drop instead of at least forty volts as relied vupon in suchconstructions.

It has also been proposed to break up a single alternating current are into many short arcs in series by causing the arc to be driven into a stack of spaced'copper plates. The theory on which these constructions are based is that the arc will be sustained across these plates until the current comes to a zero point in changing its phase. During the period of zero current the arc path experiences a deionization effect and under proper conditions reignition of the arc is prevented. In these constructions the potential drop of three hundred volts for each arc gap is relied upon as a basis for determining the number of arc gaps necessary to prevent reignition of the arcs.

In the' present invention a new principle is utilized in the construction of a multiple gap circuit breaker for improving the operation of such apparatus. This new principle is based upon the fact that a cathode potential drop exists in an arc gap which is of a constant value for any particular terminal contact material and gas surrounding the contact, irrespective. of the size or shape of the terminal, the current strength of the circuit or the length of the gap. We have found that this cathode potential drop is instantaneously developed-with the separation of the contacts for minute distances and does not vary with changing conditions of the arc.

One of the objects of the present invention is to provide a novel method of improving circuit interruption by a multiple gap switch which utilizes the additive cathode potential drop of a series of arc gaps introduced into the circuit to stop the current flow by causing circuit instability due to the inability of the circuit voltage to supply the cathode potential drop of the last gap to be introduced. Another object of the present invention is to provide a novel method of producing circuit interruption by a multiple gap switch, by which the variable nature of the anode fall and positive column drop is not depended upon to bring about current interruption.

Another object of the present invention is to provide a novel method of improving circuit interruption with a multiple gap switch by which the rate of circuit interruption is dependent only upon the rate of introducing the gaps.

Another object of the present invention is to provide a novel method of improving circuit interruption with a multiple gap switch by which deterioration of the contact materials in the circuit breaker is prevented.

Another object of the present invention is to provide a novel method of producing circuit interruption with an auxiliary multiple gap switch by which arcing at the main switch is prevented.

Another object of the present invention is to provide novel forms of multiple gap circuit breakers in which the elements are so constructed and arranged as to incorporate the method of current interruption of the present invention.

These and other objects will become more apparent from the following description and drawings in which novel forms of circuit breakers are illustrated more or less schematically for carrying out the method of the present invention and in which like reference characters denote like parts throughout the several views.

In the drawings,

Fig. 1 is a reproduction of an oscillogram illustrating the potential drop characteristics of an are for increasing arc length from the instant of ignition until extinction;

Fig. 2 is a perspective view of one form of circuit breaking apparatus incorporating the method of the present invention;

Fig. 3 is a cross sectional view oi the'plate and spacer construction of the circuit breaker shown in Fig. 2;

Fig. 4 is another embodiment of circuit breakbreaking apparatus for utilizing the method of the present invention;

Fig. '7 illustrates a rotary type of circuit breaking apparatus which may be utilized for carrying out the method of the present invention;

Fig. 7a is a side and end elevation of the movable plates illustrated in Fig. 7, showing the contour of the contacting surfaces;

Fig. 8 illustrates a second rotary type of circuit breaking apparatus which may be used to incorporate the method of the present invention;

Fig. 8a is a side and end elevation of the movable plates illustrated in Fig. 8, showingthe contour of the contacting surfaces.

Fig. 9 is a circuit diagram in which the circuit breaker of the present invention may be advantageously used;

Fig. 10 is a diagrammatical view of a circuit in which the novel circuit breakers of the present invention are used to prevent arcing at the current carrying terminals of the main switch;

Fig. 11 is a detail view of a different form of spacer element used between the groups of plates for creating a radial magnetic field;

Fig. 12 is a preferred embodiment of circuit breaking apparatus incorporating the present invention and similar to the embodiment illustrated in Fig. 2 but of diiferent form and with means for creating a radial magnetic field; t

Fig. 13 is a diagrammatical view of a circuit similar to the circuit illustrated in Fig. 10, but including windings for creating a radial magnetic field as in Fig. 12;

Fig. 14 is a perspective view of another embodiment of circuit breaking apparatus incorporating the method of the present invention;

Fig. 15 illustrates a complete circuit breaker embodying the features discussed in conjunction with Fig. 12.

It has been found that'the total potential drop across an are between two spaced terminals in an electrical circuit includes the anode potential drop, the arc fall or positive column drop, and the cathode potential drop. As stated above, the anode drop is a variable quantity depending upon the size and shape of the anode as well as the nature of the -gas and its degree of ionization, and may be either positive or negative insign. The positive column potential drop in the arc itself is also a variable quantity depending upon the current strength of the arc and the length of the arc. Because of the variable characteristics of these anode and positive column potential drops between the terminals, if they are depended upon to interrupt the current, it will be necessary to resort to lengthening the arcs to bring about interruption. Moreover, the amount of lengthening depends upon circuit conditions which may alsobe variable.

However, our experiments have shown that always when an arc is formed, an initial small potential drop develops across the arc. Further, we have been able to identify this initial small potential drop across the arc with the cathode potential drop of the active gas in the arc. This initial small cathode potential, drop develops within .0001 seconds or practically instantaneously and will hereinafter be termed instantaneous in the specification and claims. It has also been found that this instantaneously developed potential drop is of the same constant of electrodes from the instant the arc is struck until it is lengthened to the point of circuit instability. In this diagram the straight line between E0 and E1 represents the instantaneous cathode potential drop when the contacts are first separated, and E2 is the voltage which occurs at the instant of current'interruption. The increase in potential drop between E1 and E2 represents the column potential drop together with the anode potential drop. However, the curve between E1 and E2 is not reproducible and may vary over a considerable range but the total potential drop across the arc will never be less than the value of El, which corresponds to the cathode potential drop of the active gas.

The value of E1, or cathode potential drop, for any combination of electrode material and gaseous atmosphere is a constant; and can be determined experimentally. The following table, by way of example, gives experimentally determined values of the cathode potential drop for several combinations of electrode materials The method of the present invention in its broadest aspect utilizes this reproducible and rapidly developed cathode potential drop of the arc to effect current interruption. The method provides that the number of gaps be determined by the ratio of the line voltage and the cathode potential drop of the arc. The gaps determined in the above manner may be introduced simultaneously or progressively, and different results will be obtained. Instantaneous current interruption may be efiected by simultaneously introducing the gaps. Here instantaneous refers to the short time interval in which the cathode potential drop phenomena are developed. Current interruption within a predetermined time interval may be effected by introducing the gaps at a predetermined rate.

According to the method of the present invention in which the number of arc gaps is defined by the ratio of the line voltage and the cathode potential drop, introduction of the gaps brings about circuit instability due to theinability of the line voltage to supply the cathode potential drop at all of the gaps that are inserted. The method of the present invention provides more gaps than will be required to bring about current interruption. As a result of this, current interruption is efiected by the introduction of the gaps as defined above, under the condition that some gap or gaps will be introduced across which no are forms.

Therefore the present invention provides a each plate when the circuit breaker methodof circuit interruption which is not sub? ject to the variations due to the positive column drop and the anode fall, as in the case of multiple gap switches of the prior art which depend upon these components of the arc voltage for current interruption. By providing that the number of gaps be determined by the ratio of line voltage and the cathode potential drop, instantaneous or controlled interruptions may be obtained. Simultaneous gap introduction results in'the inability of the line voltage to supply the cathode potential drop at every s and therefore brings about current interruption. For the case of progressive gap introduction, the current is interrupted before all of the gaps are introduced, and results in some gaps being introduced acres which no are forms.

Therefore, a novel principle is involved in multiple gap switches designed according to the present invention. In prior multiple gap switches, a multiplicity of gaps is formed, and the arcs are lengthened to bring about current interruption. That is, the three components of the arc voltage-the cathode fall, positive column drop and anode fall-are employed and are necessary for current interruption. Switches made according to the present invention cause circuit instability to be approached by the introduction of series are gaps, the number being determined by the ratio of line voltage and cathode potential drop. Actual current interruption is not dependent upon lengthening the arcs, but always occurs within the period required for the arc gaps to be introduced. It follows that the method of our invention provides that when all of the gaps are introduced there will be one or more gaps across which no arcs form during a current interruption.

In Fig. 2 a form of circuit breaking apparatus is illustrated for employing the method of the present invention. This circuit breaking apparatus includes a base 15 having two stacks of resilient plates 16 and 17 mounted thereon and arranged in a plurality of groups separated by conducting spacers. The conducting spacers between the groups of plates are provided for the purpose of limiting the maximum distortion of is closed. Without such spacers each plate would have to bend a distance proportional to the number of the plates beneath it in the stack, and for circuit breakers using2many plates this bending, in the case of the upper plates, may be greater than permitted by the elastic limit of the plates. The plates of each group are illustrated as of square contour and adapted for vertical movement and are guided in such movement by posts 18 which loosely engage the edges of the plates, although any other suitable contour of plates and guiding means may be employed. Terminal posts 19 and 20 areprovided adjacent each stack of plates and have current conducting members 21 and 22 respectively, engaged by the terminal bottom plate of the adjacent stack for forming an electrical connection. Between the stacks of plates a bridging member 23 is provided having arms 24 and 25 engaging the top'plate of the stacks 16 and 1'7 respectively, for completing an electrical circuit between the top plates of each stack. Any suitable means may be provided for moving the bridging member 23.

As more clearly shown in Fig. 3, between the plates of each group of plates 26 and 2'1, strips of insulating material 28 are provided at the. edges to properly space the plates from each to prevent the strips of insulatbe discontinuous to permit venting of the gas between the plates. This insulating strip may consist of paper or other suitable material of such thickness that the plates will be spaced a distance sufllcient to prevent contact in spite of slight surface irregularities. We have found .005 inch to be adequae, but it istobeunderstoodthatthisvaluemaybechanged over a wide range without departing from the present invention. In this Fig. 3 the conductive spacers between the groups of plates 26 and 27, a set from being formed in the plates, are shown at 29 centrally positioned in the stack. With this construction, when pressure is applied at the center of the top plate of a group, the centers of all of the plates in the group will be forced into contact with each other to form a continuous electrical circuit.

with the construction thus far described, downward movement of the bridging member 23 will cause the plates of the outermost groups of both stacks to be moved into engagement with each other, and through the conductive spacers the succeeding groups of plates are moved into engagement as previously explained, until all plates of all groups are n conducting relation; forming a continuous circuit from the terminal 19, through conductng member 21 to the bottom of the stack of plates 16, throughthis stack of plates, through bridging member 23 to the top plate of the stack 17, and through this stack of plates to the conducting member 22 and terminal 20. Vice versa, when the circuit breaking apparatus is in a closed position, upward movement and release of pressure by the bridging member 23 will allow the resiliency of the plates to return the plates to their normal spaced relation, which will form a series of gaps in the circuit between the spaced plates.

Apparatus as shown in Fig. 2 or any other embodiment of our invention may be actuated by any suitable mechanism which will allow the contacting members to be clwed and released in the p p r manner.'

This circuit breaking apparatus may be used in the atmosphere or may be enclosed in a container with any suitable gas or liquid at any desired pressure. The plates may be of any suitable material to give the desired characteristics of cathode potential drop, while the thickness is so regulated that the resiliency will normally 'maintain the plates separated and. when released to open the circuit, properly restore the plates to their separated relationships. The number of arc gaps necessary for the particular circuit in whichtheapparatusistobeinstalledwillbe determined by the quotient of the circuit potential divided by the cathode potential drop in an are characterized by the particular material and gaseous atmosphere in which the arcs operate. This quotient will then indicate the number of arc gaps necessary from which may be determined the number of plates necessary. The number of gaps actually used will be such as to insure a margin of safety in interrupting the current, due to the inability of the line voltage to supply the cathode drop of the last gap to be put into the circuit.

In the construction of Fig. 2 the rate of separation of the plates, although rapid, is progressive, because the plates adjacent to the spacers must, by forces due to elastic distortion, contribute to the acceleration of the mass of the plates above. This progresive separation of other. Where n at; ing material may plates requires time during which the gaps are introduced in the circuit. However, this rate of introduction of gaps can be controlled by the choice of plates of proper elastic properties and thickness and also by proper thickness of insulation between the plates, or the rate of gap 'introduction may be controlled by so arranging the operating mechanism of the switch that, on opening, the moving element releases the pressure on the plates at the desired rate.

In Fig. 4, a different embodiment of circuit breaking apparatus is illustrated from that disclosed in Fig. 2, but which is adapted to incorporate the method of the present invention and have the same salient characteristics. In this construction groups of spaced plates 35, 36, 37, 38 and 39, similar to the groups 26 and 27 illustrated in Fig. 3 and of any suitable shape, are positioned on a support 40 with the end plate of the group 35 engaging a terminal 41 and the end plate of the group 39 engaging a terminal 42. Between each group of plates conducting cam members 43, 44, 45 and 46 are provided which move the plates of each group into conducting relation with each other and form a continuous circuit from the terminal 41 to the terminal 42. Although a cam mechanism is illustrated in the figure, it will be obvious to those skilled in the art that other mechanisms may be used. When the circuit is opened, as is illustrated in Fig. 4, the resiliency of the plates of the groups 35, 36, 37, 38 and 39 cause the same to be spaced from each other and form a plurality of gaps in series in the circuit. The number of gaps,.as described in the previous embodiment, will be determined according to the principle of this invention.

Fig. illustrates another embodiment of circuit breaking apparatus similar to the circuit breaking apparatus shown in Fig. 4, but in which groups of spaced plates are differently arranged. In this embodiment spaced supporting members 47 and 48 have opposing groups of spaced plates 49 and 50 mounted thereon. Two opposed pairs of groups ofplates only are illustrated, but any number of pairs necessary for circuit interruption may be provided. Terminals 51 are alternately arranged on each support and engage the bottom plate of adjacent groups of plates in pairs, so that the circuit is completed from the bottom plate of one group to the bottom plate of another group on the same support, and then from the bottom plate of the opposing group to the bottom plate of the adjacent group on the other support. Between these opposed groups of plates a shaft 52 extends, having cams 53 which, when rotated by the shaft to one position, will engage the outer plates of opposing groups and compress the plates of each group into engagement with each other to form a continuous circuit, and when rotated to another position, will form the necessary plurality of gaps in the circuit to stop the current flow. Again, as stated in reference to Fig. 4, other suitable mechanisms can be used in place of the cams illustrated in the figure. With this arrangement of plates as with other forms shown the rate of introducing the gaps into the circuit may be controlled by proper adjustment of the cam or other actuating mechanism.

In Fig. 6, another embodiment of circuit breaking apparatus is illustrated in which the contact members are longitudinally movable with respect to each other and the current flow is in a vertical direction, as illustrated in the drawings.

In this construction the contact members of one group 55' are rigidly fixed at one end on an insulating support 56 and at their other ends terminate in bevelled faces 57-and 58 with an extending fin 59 at the apex of the bevelled faces. The opposing contact members 60 are of the same general construction, being fixed at one end to an insulating support 61 with their bevelled faces positioned between the bevelled faces of the group of contacts 55 and having fins 62. When the opposing contacts 55 and 60 are brought into enagement with each other a circuit will be formed between the engaging bevelled faces and current will flow in a vertical direction as viewed in the drawings. When the insulating supports 56 and 61 are moved away from each other and thebevelled faces are out of contact with each other, a plurality of arc gaps are formed. As in all of the constructions, the number of gaps provided will be at least equal to the quotient of the circuit potential divided by the cathode potential drop of each gap. With this construction the gaps will be instantaneously introduced and the interleaving fins 59 and 62 between the adjacent contact members will prevent the formation of a continuous are between the adjacent contacts which would have the characteristics of one are only.

In Fig. 7 an embodiment of a rotary type of circuit breaking apparatus employing the method of the present invention is illustrated in which the current flow is in a vertical direction as viewed in the drawings. In this construction a plurality of spaced annular plates 63 are fixed on a suitable support 64 with adjacent pairs of plates electrically connected together as at 65. Within the fixed annular plates a rotatable shaft 66 is provided which carries spaced circular plates 67 that extend between the spaced stationary plates 63, with the pairs of plates electrically connected together as at 68 but alternately with respect to the pairs of stationary plates that are electrically connected at 65. As more clearly shown in Fig. 7a, the plates are provided with curved inclined contacting surfaces 69 that gradually increase from the plane of the plate to their final height. These inclined contacting surfaces are preferably stamped from the surface of the plates but may be formed in any other suitable way. Both the stationary and rotatable plates 63 and 67 are provided with these inclined surfaces but in reversed relation, so that in one position of the shaft 66 the contacting surfaces 69 on the plates 67 form a tight wedging engagement with the contacting surfaces 69 on the plates 63 and form a continuous circuit in a vertical direction as viewed in the drawings through the contacting surfaces of the plates. When the shaft 66 is rotated to open the circuit the inclined contacting surfaces on the plates 67 are moved away from the contacting surfaces on theplates 63 to form a plurality of arc gaps in series, the number of gaps being dependent upon the cathode potential drop for the particular material used and the voltage of the circuit in accordance with the method of the present invention. In this construction all of the gaps will be instantaneously introduced into the circuit.

In Figs. 8 and So another embodiment of circuit breaking apparatus is illustrated similar to the embodiment illustrated in Fig. 7 and Fig. 7a, including the spaced annular plates 63 fixed to a support 64 and rotatable plates 67 on a shaft 66 in spaced interleaving relation. However, in this embodiment there are no connecting means between the pairs of plates and the plates themsurfaces on the stationary and rotatable plates are reversed in their direction of inclination respectively, so that in. one position of the shaft 66 the contacting surfaces are all in engagement to form a continuous circuit in a vertical direction as viewed on the drawings but when rotated to mother position will form a plurality of arc gaps in series. -The number of gaps will be dependent upon the cathode potential drop and the potential of the circuit as in the embodimentof Figs. 1 and la andthe gaps will be simultaneously introduced into the circuit to give instantaneous circuit interruption.

Inl'ig.9,acircuit diagramisshowninwhich the circuit breaking mechanism of the present invention is embodied. In this circuit, a bridging member 76 is illustrated for forming a continuous circuit between the terminals 7'! and 78 of the line. Shunted around the main bridgi contact '16 a multiple gap circuit breaker employing the method of the present invention is illustrated diatically at 79 with a switch 80 in the shimt circuit. In opening, the circuit to stop the current fiow the switch'80 and the multiple gap circuit breaker '19 are closed to. form a path for the current flow and the main bridging contact -'16 is then opened. Following this the multiple gap circuit breaker '19 is opened to insert-a plurality of gaps into the circuit, the number of which is determined according to the principle of this invention. The sequence of operating the elements .76, 79 and 80 may be controlled by any suitable interlocking mechanism.

whiletheoperationofthemechanismmaybe either manual or automatic.

In Fig. 10 a circuit is illustrated in which the circuit breaking m of the present invention is utilized as in Fig. 9 but with added auxiliary circuit interrupters, made according to the present invention, to prevent arcing at the main current carrying bridge 76 when the main cir-- cult is opened by this member. The auxiliary internrpters 81 and 82 shown in Fig. 10 are necessary if the voltage drop across the multiple gap interrupter 83'when used alone is equal to or greater than the sum of the cathode potential drops which would-occurin arcs atthe bridging member 76. In this illustrated embodimentfa plurality of multiple gap circuit breakers 8 1, 82

and83areprovidedinparallelwiththemain breaker 76. For current interruption the switches 84, and 86 are first closed which provides parallel paths for the current, through multiple gap circuit breakers 81, 82 and 83, after which the main bridging contact-76 is opened. Next the multiple gap breaker 81 is opened. in which the number of gaps inserted into the circuit is determined according to the principle of this invention with the voltage drop which occurs across 82 and 83 in parallel. When the current through 81hasbeeninterruptedtheswitch 84isopened which insulates multiple gap breaker 81 from the line voltage. The multiple gap breaker 82 is next openedand the current flowing through it is in terrupted by the insertion of gaps in series, the number of which is determined according to the principle of this invention but based on the voltage drop acros multiple gap circuit breaker 83. switch 85 is then opened to insulate breaker 82 from the line voltage. After this the main multiple gap breaker 83 is opened which causes current interruption according to the principle of this invention. Switch 86 is then opened to insulate the main multiple gap breaker 83 from line voltage.

The diagram of Fig. 10 shows a circuit arrangement only and is not intended to fix the number of auxiliary multiple gap circuit breakers to be used. The switches 84, 85 and 86 may be left closed when current is flowing through the bridging member 76 if the heating, due to the current fiow through multiple gap breakers 81, 82 and 83, is within safe limits.

To prevent overheating and damage of the contact material in our circuit breaker, caused by the duration of the arcs in the case of a controlled rate of current interruption, a construction is provided in Fig. 11 for creating a radial magnetic field. In this construction the spacer element provided between adjacent groups of plates as shown in Fig. 2 is made in' the form of a conductive helix 89 which has its contour filled with insulation 88 to form a solid body. This helical conductive spacer element is adapted to be placed between the bottom plate 90 of one group of plates andthe top plate 91 of the adjacent group of plates- The spacer elements may be of any convenient helical or spiral form with suificient number of turns to create a radial magnetic field or sufiicient strength to move the arcs with hi velocity.

In Fig. 12 a preferred construction of circuit breaker is illustrated in which a radial magnetic field is used to move the arcs. In this embodiment the plates 93 are of annular form, arranged in groups, and spaced from each other at their edges by strips of insulating material not shown in the figure but similar to that illustrated in Fig. 3. Between each group of plates annular spacer elements 94 are provided which perform the same functions as the spacers 29 in Fig. 3. If desired, a plurality of stacks of such groups of plates may be used with a bridgin member to function in a similar manner to the embodiment illustrated in Fig. 2. However, in this construction a tubular insulating sleeve 95 is inserted in the opening at the center of the annular plate which contains a plurality of reversed windings 96, 9'1 and 98. These coils 96, 9'7 and 98 are connected in series with the terminal leads connected in the line on either side of the circuit breaker or in any other suitable way to give the proper voltage drop and current flow.- With this arrange ment, as long as there is current fiowing in the circuit a radial magnetici'field will be present which will move the arcs and prevent a deterioration of the contact material by fusion. The magnetic circuit may be improved by use of a shell of magnetic material surrounding the tube of insulating material 99. Further improvement may be obtained by use of cores of magnetic material inthe coils 96,9'7and 98. v

Fig. 13 illustrates an arrangement of elements to include the salient features of the embodiments shown in Figs. 10 and 12. This arrangement includes, as in Fig. 10, three multiple gap circuit breakers 81, 82 and 83 and disconnect switches 84, 85 and 86 shunted about a main bridging contactor '16. However, in thisconstruction reverse windings 100 and 101 are connected in the circuit of the multiple gap circuit breaker 83 for creating a radial magnetic field, as in the embodiment, illustrated in Fig. 12.

Similarly multiple gap circuit breakers s1 and s2- have reversed windings 102, 103, and 104, 105 respectively.

In Fig. 14 another embodiment of circuit breaking apparatus is illustrated which is particularly adapted for the control of motors and like apparatus. This embodiment which may be enclosed in a casing of insulating material includes a base plate 106 of suitable insulating material on one surface of which are mounted spaced terminal blocks 107 and 108 of conducting material having recesses on their upper surfaces. path of less diameter than the distance between said blocks a pair of inclined cams 109 and 110 are provided on the same surface of the plate as the terminal blocks. A shaft 111 adapted for both rotary and longitudinal movement extends through the plate 106 and is provided with a bridging arm 112 properly insulated from the shaft 111 and extending on either side of the shaft. This bridging arm 112 is in the form of a rod sufiiciently long to extend between the ter- 'minal blocks. Rollers 113 and 114 are mounted on the bridging arm on opposite sides of the shaft and at a distance from the shaft such that they will move in the same circular path in which the cam members are positioned. The end of the shaft 111 is recessed as at 115 to contain a spring 126 and to frictionally engage a shaft extension 116 the opposite end of which is recessed at 117 for engaging a spring 118 adjustably tensioned by a screw cap 119 which is held by a support not shown in the figure. In this manner the shafts 116 and 111 are yieldably forced toward the plate 106 and this movement is resisted by the bridging member 112.

The construction thus far described with the I bridging member 112 in the position shown across the terminal blocks 107 and 108 operates as follows: Rotation of the shaft 111 in the direction of the arrow with sufiicient force to release the ends of the bridging member from the recesses in the terminal blocks 107 and 108 will cause the bridging member to move away from the blocks 107 and 108 to and then off of themsulating blocks 120 and 121 and thereby open the main circuit. To again establish the circuit the shaft 111 is further rotated in the same direction which will cause the rollers 113 and 114 on the bridging arm 112, to ride up on the inclined cams 109 and 110 to a position directly over the terminal blocks. The cams 109 and 110 end at this position so that further rotation of the shaft will cause the rollers to ride off the cams and engage and bridge the blocks with a quick engagement.

An auxiliary multiple gap circuit breaker is provided in accordance with the method of the present invention to open the circuit when the bridging member moves out of engagement with the terminal blocks. To this end a series of stationary circular plates 122 are provided that are preferably made in separate halves insulated from each other, and fixed in parallel spaced relation with each other. Cooperating rotary plates 123 fixed to the shaft extension 116 extend between the fixed plates and the cooperating plates are provided with contacting surfaces adapted to be engaged to form a continuous circuit when the shaft extension 116 is moved longitudinally due to cam surfaces 109 and 110. It will thus be apparent that when the bridging arm 112 moves up the cams to bridge the terminal blocks 107 and 108 a closed circuit is first formed in the multiple gap circuit breaker and Between these blocks and in a circular vice versa the multiple gap circuit breaker will not be opened until after the bridging member has left the terminal blocks so that the circuit is opened by the multiple gap breaker and arcing and deterioration of the main breaker is prevented. One terminal block is connected to one of the halves of the lower stationary plate, and the circuit is completed by the lower rotating plate as a bridging member across to the other half of the lower stationary plate. The current is then carried by a fixed connection to the half of the next plate directly above the second half of the first plate and across to the other half of the second stationary plate by the second rotating plate and so on through the whole stack of plates to form two gaps in series for each pair of plates.

The particular contact surfaces between the rotary and stationary plates have not been illustrated as such will be understood from the description of the previous embodiments, and as various arrangements may be had within the scope of the invention. However, conductors 124 and 125 will be provided between the respective terminal blocks 107 and 108 and the stack of plates to complete the circuit between the main breaker and the multiple gap breaker.-

With this construction the frictional engagement between the shaft 111 and its extension 116 provides for a slight relative rotation between the plates to insure a clean contacting surface. Instead of rotating plates a stack of plates similar to that illustrated in the embodiments of Figs. 2 and 12 may be advantageously used in this construction. In this modification the number of plates will be determined by the number of gaps required in accordance with the method of the present invention.

In Fig. 15, which shows in section a circuit breaker embodying features discussed in conjunction with Fig. 12 and which in many respects is comparable in construction to the circuit breaker of Fig. 2, a base has two stacks of annular resilient plates 131 and 132 mounted .thereon and arranged in a plurality of groups,

here shown as three each, said groups being separated by conducting spacers 134. The plates of each group are spaced at their peripheries by strips of insulating material 133, and said plates are guided in their movements by the enclosing tubular walls 135 which may have an exterior shell of magnetic material surrounding an interior insulating sleeve. A bridging member 136 has at its opposite ends annular pressure members 137 adapted to move axially of the stacks for compressing and releasing the same. Any suitable means, as a lever 138, may be used for actuating said bridging member 13 A tubular insulating sleeve 139 is disposed in the central opening of each stack of plates, and within each sleeve are a plurality of reversed windings 140, 141, 142 which may have cores of magnetic material and which are connected in series by leads 143 and 144. Current flowing in said coils produces a radial magnetic field, as heretofore explained, whereby the arcs are rotated as described. The circuit through said circuit breaker extends from terminal 145 through 'lead 146 to the endmost spacer 134 associated leads 143 and 144. A main bridging member 149 may also be employed for forming a continuous circuit between the terminals 145 and 148, in accordance with the principles heretofore explained andpointed out in conjunction with P188. 12' and 13.

From the above description it will be apparent to those skilled in the art that a novel method of circuit interruption has been provided which is dependable under all conditions to perform its function, as it is dependent only upon the constant, reproducible, and instantaneously developed cathode potential drop, and not. essentially dependent upon any variable factor which may be present. Further, it will be apparent to those skilled in the art that variousother circuit breaking apparatus may be used which employ the method or the present invention besides those described ,and illustrated in the drawings. For a definition of the limits of the invention reference is therefore to be had to the appended claims.

What is claimed is:-

1. The method of interrupting an electric current which includes introducing the potential drop of such a number of arc gaps in series in the circuit that the total cathode potential drop of all of the gaps will prevent the maintenance 0! the current by the line voltage.

2. The method of interrupting an electric circuit which includes the step or introducing into the circuit a number of arc gaps which is at least equal to the quotient of the potential of the circuit divided by the cathode potential drop of each ap- 3. The method of interrupting an electric circuit which includes the step of introducing into the circuit a number of arc gaps such that the product of said number and the initial potential drop of an arc gap which is instantaneously developed independently of the length of the gap and the strength or the current when the terminals are separated exceeds the line voltage.

4. The method 0! interrupting an electric circuit which includes the step of simultaneously introducing into the circuit a series of arc gaps not less in number than the ratio of line voltage to the cathode potential drop of each arc gap.

5. The method of interrupting an electric circuit which includes the step or rapidly and progressively introducing into the circuit a series of arc gaps not less in number than the ratio of line voltage to the cathode potential drop of each arc 8 P- 6. The method of interrupting an electric circuit which includes the step of introducing into the circuit in series such a numberof arc gaps that the cathode potential drop of said gaps cannot be supported by the line voltage and controlling the rate 01' current interruption by the rate at which said gaps are introduced into the circuit.

'l. The method of interrupting an electric circuit which includes the. step of introducing into the circuit in series such a number of arc gaps that the voltage oi'the line is unable to supply the voltage required for the cathode potential drop of all of the gaps so introduced.

8. The method of interrupting an electric circuit which includes the step of introducing into the circuit in series such a number 0! are gaps that the voltage of the line is unable to supply the voltage required for the cathode potential drop of all oi? the gaps so introduced and creating a radial magnetic, field between the terminals of the series of arc gaps.

9. The method of interrupting an electric circuit which includes shunting the current through one or more paths which are parallel to the main.

circuit and introducing into said paths a series of arc gaps of such number that the product of said number and the cathode potential drop of each arc gap is greater than the voltage applied to that path.

10. The method of interrupting an electrical circuit which includes rapidly and progressively introducing into the circuit such a number o! are gaps that prior to opening the last gap so much of the line voltage is consumed in maintaining the previously created arcs that the remainder is unable to supply the cathode potential drop required for the last gap.

11. The method of interrupting an electrical circuit which includes rapidly and progressively introducing into the circuit such a number of arc gaps that prior to opening the last gap so much of the line voltage is consumed in maintaining the previously created a'rcs that the remainder is unable to supply the cathode potential drop required for the last gap, grouping the series of arc gaps into a plurality of units, and utilizing thecurrent flow between the units to create a radial magnetic field between the terminals of each arc gap.

12. An electrical circuit maker and breaker comprising a plurality of electrodes adapted to provide a number of gaps which is greater than the quotient of the circuit potential divided by the cathode potential drop between each pair of electrodes, and means for moving said electrodes into and out of contact with each other.

13. An electrical circuit maker and breaker comprising a plurality of electrodes adapted to provide a number 01 gaps which is greater than the quotient of the circuit potential divided by the cathode potential drop between each pair of electrodes, and means for moving said electrodes into contact with each other, said circuit maker and breaker including resilient means tensioned by the contacting of said electrodes to restore said electrodes to spaced relation and introduce a series of arc gaps into the circuit.

14. An electrical circuit maker and breaker comprising a plurality of resilient plates, insulating strips between the plates for normally holding the plates in spaced relation, the number of plates being greater than the quotient of the circuit potential divided by the cathode potential drop between each pair of plates, and means for moving the plates into contact with each other between the insulating strips.

15. An electrical circuit maker and breaker comprising a plurality of groups of resilient plates, insulating strips between the plates of each group for normally holding the plates in spaced relation, conducting spacers between successive groups of plates, the total number of plates in all or the groups being greater than the quotient of the circuit potential divided by the cathode potential drop between each pair of plates, and means cooperating .with the conducting spacers for movingall oi the plates into conducting relation with each other between the insulating strips.

16. In an electrical circuit maker and breaker comprising -two stacks of resilient plates arranged in a plurality of groups, insulating strips between the plates for normally holding the plates in spaced relation, conducting spacers between "successive groups of plates, the total numher of plates being greater than the quotient of the circuit potential divided by the cathode potential drop between each pair of plates, and a bridging piece adapted to be moved into electrical contact with both stacks of plates and cooperating with the conducting spacers to move all of the plates in both stacks into conductive relation for forming a continuous circuit.

17. An electrical circuit maker and breaker comprising a plurality of normally spaced electrodes, the number of electrodes being greater than the quotient of the circuit potential divided by the cathode potential drop in an are between each pair of electrodes, means for moving the electrodes into contact with each other, and means for creating a radial magnetic'field between the electrodes.

18. An electrical circuit maker and breaker comprising a plurality of normally spaced electrodes, the number of electrodes being greater than the quotient of the circuit potential divided by the cathode potential drop of the arc between each pair of electrodes, means for moving the electrodes into contact with each other, and means utilizing the current flowing through said electrodes for creating a radial magnetic field between said electrodes.

19. An electrical circuit maker and breaker comprising a plurality of groups of resilient plates, insulating strips between the plates of each group for normally holding the plates in spaced relation, spiral conducting spacers between successive groups of plates, and means cooperating with the spacers for moving the plates of each group into conducting relation with each other, said spiral conducting spacers providing means to create a radial magnetic field between the groups of plates when said plates are sepa rated.

20. An electrical circuit maker and breaker comprising a plurality of groups of resilient annular plates, insulating strips between the edges of the annular plates for normally holding the plates of each group in spaced relation, conducting spacers between successive groups of annular plates positioned between the edges of the plates, and a movable annular member adapted to cooperate with the conducting spacers to move the plates of each group into engagement with each other to form a continuous electrical path.

21. An electrical circuit maker and breaker comprising a plurality of groups of annular resilient plates, insulating strips between the edges of the plates of each group for normally holding the plates in spaced relation, conducting spacers between successive groups of plates positioned between the edges of the annular plates, a movable annular member adapted to cooperate with the conducting spacers for moving the plates of each group into conducting relation with each other, and a plurality of electrical windings within the annular plates for creating a radial magnetic field.

22. An electrical circuit maker and breaker comprising a plurality of stacks of annular plates divided into a plurality of groups, insulating strips between the edges 01 the plates of each group for normally holding the plates in spaced relation, conducting spacers between successive groups of plates, a movable bridging member having an annular member at each end adapted to cooperate with the conducting spacers for moving the plates of each group into conducting relation witheach other, and a plurality of opposed windings within each stack of annular plates and connected in the circuit so as to produce a radial magnetic field between the plates.

23. An electrical circuit maker and breaker comprising a pair of spaced supports, a plurality of groups of spaced resilient plates on each sup- I port opposite each other, conductors between alternate adjacent groups of plates on each support in staggered relation, and a shaft having conducting members between each pair of opposed groups of plates adapted when rotated to simultaneously move the conducting members into engagement with the inner plates of the opposed groups and compress the plates of each group into engagement with each other.

24. An electrical circuit maker and breaker comprising a plurality of stationary electrodes, a plurality of movable electrodes, the electrodes of said groups having surfaces adapted to engage each other and the number of arc gaps formed at these cooperating contacting surfaces being at least equal to the quotient of the circuit potential divided by the cathode potential drop of the arc between eachpair of contacting surfaces, and means for simultaneously moving the electrodes of one group into and out of engagement with the electrodes of the other group.

25. An electrical circuit maker and breaker comprising a stationary support having a plurality of stationary electrodes formed with contact surfaces, and amovable support having a plurality of electrodes formed with cooperating interleaving contact surfaces, said electrodes having cooperating wedging surfaces and said movable electrodes being adapted to form a plurality of arc gaps in the circuit inseries simultaneously upon movement of said movable support.

26. An electrical circuit maker and breaker comprising a stationary support having a plurality of stationary electrodes formed with contact surfaces, a movable support having aplurality of electrodes formed with cooperating interleaving contact surfaces, said contact surfaces having a wedging contact and said movable electrodes being adapted to form a plurality of arc gaps in the circuit in series simultaneously upon movement of the support, and a fin projecting from each electrode between an opposing pair of electrodes..

27. An electrical circuit maker and breaker comprising spaced terminals in an electrical circuit, a main bridging member for closing the circuit between the spaced terminals, and an auxiliary means for conducting current shunted around the main bridging member including a series of normally spaced electrodes adapted to be moved into engagement with each other and when separated form a plurality of arc gaps in series, the number of arc gaps being not less than the quotient of the circuit potential divided by the cathode potential drop of each arc gap.

28. An electrical circuit maker and breaker including a main bridgingt contact for closing the circuit between spaced terminals in the electric circuit, and a plurality of multiple gap circuit breakers connected in parallel with the main bridging contact, each having at least a number of arc gaps in series equal to the quotient of the voltage applied to. that path divided by the cathode potential drop for each arc gap.

29. An electrical circuit maker and breaker including a main-bridging contact for closing the circuit between spaced terminals in the electric circuit, and a plurality of multiple gap circuit breakers connected in parallel with the main bridging contact and each having at least a number of arc gaps in series equal to the quotient of the voltage applied to that path dividedby the cathode potential drop for each arc gap, and a series of coils having reversed windings for erating a radial magnetic field between the arc gaps of the multiple gap circuit breakers which shunt the main bridging contact.

30. An electrical circuit maker and breaker comprising a plurality of groups of annular resilient plates, insulating strips between the edges of the plates of each group for normally with said electrical windings for improving the 10 magnetic circuit thereof.

PAUL L. BETZ. SEBASTIAN KARRER. 

